The present invention relates to a vented fuel cap for a vehicle having a pressure-vacuum valve and a roll-over safety valve. More particularly, the present invention relates to a vented fuel cap having a pressure-vacuum valve and a roll-over safety valve mounted axially above the pressure-vacuum valve.
Fuel caps having pressure-vacuum valves and roll-over safety valves are generally known. The pressure-vacuum valve is provided in such fuel caps for venting the fuel tank to the atmosphere when the pressure in the tank exceeds a predetermined, superatmospheric level, and also when the pressure in the tank drops below a predetermined subatmospheric level. The roll-over safety valves are provided to prevent the flow of fuel through the cap if the vehicle should be rolled over to a generally inverted orientation. The pressure-vacuum valve generally includes a pair of valves that are normally closed, and which open automatically in response to predetermined changes in the pressure within the fuel tank. One valve, the pressure valve, functions to release excess vapors in the tank when the pressure exceeds a predetermined level. The second valve, the vacuum valve, functions to control the inhalation of atmospheric air when the pressure in the tank drops below a predetermined subatmospheric level. The pressure-vacuum valve arrangement is provided, and generally required, for protection of the environment.
Examples of known types of fuel caps having pressure-vacuum valves and roll-over safety valves are disclosed in U.S. Pat. No. 4,162,021 to Crute issued July 24, 1979; U.S. Pat. No. 3,985,260 to Evans issued Oct. 12, 1976; and U.S. Pat. No. 3,938,692 to Crute issued Feb. 17, 1976. The fuel caps disclosed in these patents all have a roll-over safety valve that is located below the pressure-vacuum valve of the cap. In these known caps, the roll-over safety valve is configured to be a part of the venting portion of the cap. Therefore, vapor venting from the cap, or air entering through the cap must pass through the roll-over safety valve.
One problem with these known fuel caps is that because the roll-over safety valves are located axially below the pressure-vacuum valve, the cap is generally longer axially than the outer housing of the cap. This extended length generally forces the roll-over safety valve to extend axially beyond the housing of the cap, which places the roll-over safety valve in a position where it is susceptible to breakage or other damage.
Another problem with these known fuel caps is that the roll-over safety valves are generally configured to be a part of the venting means of the cap. Thus the inflowing air, or outflowing vapor is forced to pass around the ball which may, in certain circumstances force the ball axially upwardly to prematurely seal the roll-over safety valve. It is also possible for fuel to splash into the roll-over safety valve to prematurely seal the valve.
One object of the present invention is to provide an improved pressure-vacuum valve venting fuel cap with a roll-over safety valve that is not located in a position where it is susceptible to breakage or other damage.
Another object of the present invention is to provide a pressure-vacuum valve venting fuel cap with a roll-over safety valve that is not a part of the venting means of the cap.
According to the present invention, a pressure-vacuum cap for a vehicle fuel tank having a normally upwardly extending filler neck formed with a peripherally and radially extending sealing surface concentric with the longitudinal axis of the neck is provided. The cap includes a cover and a valve housing providing a passageway extending axially therethrough and having means for connecting the housing to the filler neck. The axially upper portion of the passageway is formed to include a valve seat. The valve housing is also formed to include a peripherally and radially outwardly extending shoulder that has at least one opening formed therethrough, and a radially inwardly extending, axially upwardly facing sealing surface that is disposed around the lower portion of the passageway. A first valve member is disposed within the passageway above the sealing surface and formed to include an aperture therethrough. A first spring means for yieldably urging the first valve member axially downwardly against the sealing surface to close the passageway is provided, the spring means being calibrated to provide for movement of the first valve member axially upwardly away from the sealing surface to open the passageway when the pressure in the filler neck reaches a predetermined superatmospheric level. A second valve member is disposed below the first valve member and is concentric with the aperture in the first valve member. Second spring means for yieldably urging the second valve member axially upwardly to close the aperture in the first valve member are also provided. The second spring means are calibrated to provide for movement of the second valve member axially downwardly away from the first valve member to open the aperture in the first valve member to vent the filler neck and the fuel tank through the passageway when the pressure in the filler neck reaches a predetermined subatmospheric level. Sealing means disposed within the passageway above the first valve member are provided. The sealing means is formed to be received in the valve seat in the upper portion of the passageway when the filler neck is tilted to a substantially inverted orientation to close the passageway.
One feature of the foregoing structure is that the passageway and valve seat in the valve housing and the sealing means disposed within the passageway cooperate to form a roll-over safety valve that is disposed above the pressure-vacuum valve in the cap. One advantage of this feature is that the roll-over valve is located entirely within the housing of the cap, and does not extend axially beyond the lower portion of the housing. Another advantage of this feature is that the cap has a shorter axial dimension than was heretofore possible in such caps.
In preferred embodiments of the present invention, a series of columns are circumferentially spaced around the valve housing above the first valve member and between the first valve member and the valve seat. A circular plate is mounted on the columns and configured to support the sealing means. One feature of the foregoing structure is that, because the columns are spaced apart from each other and the columns support sealing means, the inflow of air and the outflow of vapor are routed around the sealing means to place the sealing means out of the venting path of the cap. One advantage of this feature is that because the sealing means is not part of the venting path of the cap, the sealing means cannot be forced axially upwardly by either excess vapor or splashing fuel to prematurely seal the valve seat and the roll-over safety valve.
Also in preferred embodiments of the present invention, the sealing means comprises a ball that has a density greater than the fuel in the fuel tank, and the plate supporting the ball includes a centrally disposed opening formed therein that is sized to capture a portion of the ball. One feature of the foregoing structure is that when the ball is not in use to seal the valve seat when the cap is rolled over to a substantially inverted position, the ball is captured in the support plate in a non-use position. One advantage of this feature is that the ball is not permitted to move within the roll-over safety valve when the cap is in the normal position. This greatly lessens the chances that the ball can be bounced axially upwardly to prematurely seal the valve seat to close off the venting capability of the cap.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently preceived.